This invention relates to a method for avoiding eye damage when using high-power lasers and, more particularly to a method for avoiding eye damage when using high-power lasers operating in the spectral region which is transmissible for the eye lens. One such known method is described, for example, from the publications International Defence Review", 8/1991, pp. 818-821, and Wehrtechnik, wt 1/87, pp. 55-62.
It has heretofore been known to have laser systems which have to master the various tasks in civil as well as military fields of application. These tasks include, for example, laser range finding equipment, laser Doppler radar systems, laser target illuminating and marking equipment, laser systems for the analysis of the atmosphere as well as systems with very high laser power which have as their object an interference with, but also a destruction of, the radiated material.
From the publication Wehrtechnik, wt 12/85, Pages 77 to 80, a system of very high laser power with the object of destroying the radiated material is known. The lasers used for the abovementioned applications operate in spectral regions for which the atmosphere is basically transmissible under good and fair weather conditions, as indicated in the graph of FIG. 1. These lasers particularly include the deuterium fluoride laser in the 3-5 .mu.m spectral region, the CO.sub.2 -laser in the 10 .mu.m spectral region, the neodymium laser (Nd) in the close infrared region at 1.06 .mu.m and additional lasers which operate at different wavelengths in these spectral regions achieved by the doubling or Raman shift of their output frequency.
Particularly, the high-power laser systems which have the purpose of destroying military objects as a result of the thermal effect of the absorbed laser radiation have the characteristic of temporarily interfering with or permanently destroying, over very long distances, sensors which operate in the spectral region of the laser. Corresponding to their purpose, the sensors must be highly sensitive.
From the publication Armed Forces Journal, May 1992, pp. 60 et. seq., laser systems are known which have the purpose of eliminating sensors either by an effective interference or by destruction. Lasers which are suitable for this purpose are, for example, CO.sub.2 -lasers and DF-lasers for heating imaging equipment which operate in the above-mentioned infrared bands, and the Nd-laser which--invisible to the human eye--emits at a wavelength 1.06 .mu.m and is also used with double frequency (wavelength 0.53 .mu.m) and can, therefore, be used for temporarily blinding human beings.
Because of the fact that meteorological conditions change significantly, thus affecting the reducing characteristics of the atmosphere, and because the distance to the target is frequently unknown, it is possible, however, only in rare cases to apportion the emitted laser power in the visible spectral region in such a manner that, although a temporary blinding will occur, there will now be destruction of the retina.
Nd-lasers, which do not operate by means of a double frequency, but rather by means of the base frequency and a wavelength at 1.06 .mu.m, are not visible at all. However, similarly to the visible frequency-doubled radiation, they are focussed at 1.06 .mu.m on the fundus of the eye and therefore destroy even at a relatively low occurring energy density the radiated point of the fundus of the eye without any possibility for the affected human being to react ahead of time.
There is therefore needed a method by which the danger of permanent eye damage to the operator or the observer of a high-power laser is eliminated, but which permits the unimpaired implementation of the tactical mission, for example, the destruction of a sensor.
These needs are met by a method for avoiding eye damage when using high-power lasers operating in the spectral region which is transmissible for the eye lens. A warning laser which operates in the visible region is assigned to the beam of the high-power laser. The power of the warning laser, within a short warning period, is increased from zero to increasingly higher values before the laser beam of the high-power laser reaches the eye.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.